Which pipe fitting is used for vertical to horizontal changes of direction?

The long sweep bend is specifically designed to allow for gentle changes in direction, which is critical when transitioning from a vertical to a horizontal alignment. This type of fitting minimizes friction loss and turbulence in the flow, promoting efficient drainage and preventing blockages. The longer radius of the bend supports gravity flow better than sharper bends would.

While a tee fitting can also change direction and a wye fitting allows for branching while accommodating a more gradual angle, they aren't primarily intended to facilitate a smooth transition from a vertical to a horizontal pipe section. They serve different functions in a plumbing system. A tee is typically used to connect three pipes, while the wye fitting is primarily used for connecting branch lines at less severe angles. Therefore, the long sweep bend stands out as the most suitable option for this specific change in direction.